A protocol for the ortho C-H alkenylation of aromatic and heterocyclic esters under ruthenium catalysis has been developed. Herein, we report a Cp*-free ruthenium-catalyzed direct mono-alkenylation of arene esters with cyclic enediones. The reaction proceeds through initial cyclometalation via weak chelation-assisted C-H bond activation, followed by coordination of the activated alkene, insertion into the Ru-C bond, and β-hydride elimination. Additionally, regioselective dual ortho C-H alkenylation was realized, which not only broadens the synthetic utility of the arene esters as directing groups but also enables the construction of structurally diverse, symmetrically, and unsymmetrically alkenylated aromatic frameworks in a straightforward manner.
Dharavath et al. (Thu,) studied this question.